Crankcase evacuation and oil return system

ABSTRACT

A refrigeration motor compressor unit comprising a housing separated by a partition into a crankcase compartment and a motor compartment. The partition defines an oil return passage connecting the motor compartment with the crankcase compartment, the passage having a one-way check valve mounted therein which permits a flow of fluid to take place only from the motor compartment to the crankcase compartment. The crankcase compartment defines a plurality of cylinders adapted to receive pistons therein and has a valve plate having a plurality of apertures therein mounted to it, with at least one of the apertures being a suction port. A cylinder head is mounted to the crankcase housing and is constructed to define at least one suction chamber and at least one discharge chamber. The crankcase compartment housing defines a fluid equalizing passage having one end cooperating with the crankcase compartment interior and the other end cooperating with a suction chamber of the cylinder head. A conduit member is connected to the fluid equalizing passage to direct fluid passing from the crankcase compartment through the passage towards a suction port of the valve plate.

United States Patent [19] Harris et a1.

1 Jan.30,1973

154] CRANKCASE EVACUATION AND 01L RETURN SYSTEM 175] Inventors: Bradford Foster Harris, Murray Hill; Tommaso F. Scarfone, Jersey City, both of NJ.

[73] Assignee: Fedders Corporation, Edison, NJ.

[22] Filed: June 10, 1971 [21] Appl. No.: 151,824

[52] U.S.Cl. ..l84/6.l6,184/6.5,417/372, 417/902 [51] lnt.Cl ..F0lm1/12 [58] Field of Search .....417/372, 415, 902; 184/616, 184/65; 62/469, 470; 123/119 B Primary Examiner-Manuel A. Antonakas AlmrneyKane, Dalsimer, Kane, Sullivan and Kurucz [57] ABSTRACT A refrigeration motor compressor unit comprising a housing separated by a partition into a crankcase compartment and a motor compartment. The partition defines an oil return passage connecting the motor compartment with the crankcase compartment, the passage having a one-way check valve mounted therein which permits a flow of fluid to take place only from the motor compartment to the crankcase compartment. The crankcase compartment defines a plurality of cylinders adapted to receive pistons therein and has a valve plate having a plurality of apertures therein mounted to it, with at least one of the apertures being a suction port. A cylinder head is mounted to the crankcase housing and is constructed to define at least one suction chamber and at least one discharge chamber. The crankcase compartment housing defines a fluid equalizing passage having one end cooperating with the crankcase compartment interior and the other end cooperating with a suction chamber of the cylinder head. A conduit member is connected to the fluid equalizing passage to direct fluid passing from the crankcase compartment through the passage towards a suction port of the valve plate.

18 Claims, 5 Drawing Figures mmmmo @973 3.713.513

sum 1 or 2 W INVENTORS m afioeamwe/s ATTORNEYfl CRANKCASE EVACUATION AND OIL RETURN SYSTEM The invention generally relates to refrigeration systems and more particularly to means for maintaining proper lubrication of compressors.

In refrigeration systems utilizing self-contained motor compressor units in which the returning refrigerant is used to cool the motor and where oil is carried throughout the system, the crankcase pressure must be maintained at a sufficiently low or equal pressure relative to the rest of the system to permit the return of lubricant collected in the motor compartment to the crankcase. The lubricant with entrained refrigerant in the crankcase generally foams at the starting period of compressor action and the foamed oil tends to be drawn from the crankcase into the refrigeration system. In the crankcase, piston blow-by occurs which makes it difficult to maintain crankcase pressure at a sufficiently low level since the blow-by past the piston rings into the crankcase causes the crankcase to constantly have a higher pressure than the motor cavity. The oil or lubricant which has been lost from the crankcase travels through the system and returns with the suction gas, where it accumulates in the motor cavity. If there is no way of returning this oil to the crankcase, a condition may come about whereby the quantity of oil in the crankcase will be below a desired level, which can cause damage to the compressor.

It is known in the art to try to equalize the crankcase and the motor cavity pressure by using a conduit having a check valve therein which leads from the crankcase cavity to the intake manifold. Such prior art is disclosed in U. S. Pat. No. 3,123,287. It is also well known in the art to use a return check valve leading from the motor cavity to the crankcase to allow the lubricant to flow from the motor cavity to the crankcase.

In the present invention, the pressure between the motor cavity and the crankcase is continuously equalized by the use of an oil equalization passage and conduit means toassure that oil will be returned to the crankcase under all operating conditions by effective use of the pumping action inherent in reciprocating compressors.

This novel and improved construction for venting the crankcase and maintaining lubricant supply is accomplished by a simple, trouble free construction which does not interfere with the other portions of the refrigerating system.

Other features and advantages of the invention will be apparent from the following description of the embodiments of the invention as shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings, the motor compressor unit is generally indicated at 10 and comprises a housing 12 separated by a partition 14 into a motor compartment 16 and a crankcase compartment 18. The partition 14 has an aperture 20 through which a motor shaft 22 extends and an aperture 21 forming a passage which allows the motor compartment to communicate with the crankcase compartment. The shaft 22 is driven bythe motor 24 positioned in the motor compartment, the motor being operated by a source of power not shown. Connected to the shaft 22 is a crankshaft 26 having connecting rods 25, only one of which is shown, transmitting the drive from the crankshaft 26 to a piston 27. Each piston 27 is disposed in a cylinder 28 of the compressor, as shown in FIGS. 1, 3 and 4. A valve plate 30 covers a portion of the crankcase including cylinder 28 and has a plurality of apertures forming at least one suction port 32 and at least one discharge port 34. A cylinder head 36 covers the valve plate 30 and is constructed to form at least one suction chamber 31 and at least one discharge chamber 35. The cylinder head 36 is preferably mounted or secured to the crankcase compartment 18 by suitable means 37.

Suction gas therefore passes from motor compartment 16 through suction passage 29 of valve plate 30 into suction chamber 31.

The above description sets forth a standard hermetic motor compressor known in the art so that the invention can be described in relation to the parts of a standard motor compressor unit. In the preferred embodiment of the invention, a fluid equalizing channel or passage 40 is drilled or cast in the wall of the cylinder 28 so that passage 40 connects a cylinder head suction chamber with the crankcase compartment cavity. The valve plate 30 has an aperture 42 aligned with passage 40, the aperture being threaded to receive a curved conduit member 44. The conduit member 44 positively directs fluid flowing from the higher pressure area of the crankcase cavity toward suction port 32 and into the chamber of cylinder 28. The conduit member 44 has one end threaded to cooperate and fit in the threaded valve plate aperture 42. The other end of conduit member 44 is formed such that the crankcase fluid is directed towards suction port 32, thereby utilizing the flow inducement created by the high velocity suction gas pressing around the tip of conduit member 44 into suction port 32.

In the preferred embodiment the conduit member 44 is generally U" or J shaped. If desired, a plate having a channel or passage therein can be substituted for the conduit member 44 so that the fluid passing from the crankcase is directed from passage 40 through the plate channel or passage toward or to the suction port 32.

In an additional modification of the embodiment as shown in FIG. 4, the valve plate 30 is suitably channeled or formed to interconnect with the passage 40 to direct the gas from the crankcase into the suction port. While the embodiment in FIG. 4 shows a plate 46 mounted to cooperate with valve plate 30 to form channel 48, the valve plate body itself can be channeled to form a passage.

A one-way oil return check valve 50, as shown in FIGS. 1 and 5, is inserted in aperture 21 of the partition 14 so that lubricant can flow from the motor compartment into the crankcase compartment. Preferably, both the check valve assembly 50 and aperture 21 are threaded so that the check valve assembly can be screwed into the partition aperture 21. The check valve assembly 50 preferably has a ball 52 which can be seated in valve seat 54 and maintained in place by a retaining ring 56. The ball 52 has a diameter which is slightly greater than valve channel 58 in the valve assembly and the interior diameter of the retaining ring 56 so that it is kept in place.

In operation of the invention, the reciprocating action of the piston 27 will cause refrigerant gas from the suction chamber to flow through suction port 32 and suction valve 33 into the cylinder chamber. As the piston 27 moves on the downward or suction stroke, reduction in pressure is reflected in conduit member 44 and passage 40 due to the high velocity of the suction gas through suction port 32. Since passage 40 communicates with the crankcase, blow-by gas and refrigerant boiling out of the oil are evacuated toward the suction port 32 from the passage 40 and conduit member 44.

When utilizing the invention, at all operating conditions, the pressure in the motor cavity 16 is higher than or substantially equal to the pressure in the cylinder head suction chamber. Evacuation of the blow-by gas through passage 40 assures that the crankcase pressure will be lower than the motor cavity, thus permitting oil or lubricant that has accumulated in the motor cavity to return to the crankcase through check valve assembly S0.

The check valve assembly 50 has a ball 52 which will close against seat 54 when the pressure in the crankcase rises above the pressure in the motor cavity, thus sealing off the crankcase from the motor cavity. This condition will occur during either start-up or shutdown of the compressor.

The above invention is thus simpler and more efficient than previously used complex mechanical means utilized to evacuate the crankcase and differs in that it achieves a desired result from the effective use of the pumping action inherent in reciprocating compressors.

While the preferred embodiment of the invention has been disclosed, it is understood that the invention is not limited to such an embodiment since it may be otherwise embodied in the scope of the appended claims.

What is claimed is I l. A hermetic refrigeration motor compressor unit of the type having an oil return check valve passage leading from the motor compartment to the compressor crankcase compartment comprising a one-way check valve disposed in said oil return check valve passage to allow oil only to flow from said motor compartment to said compressor crankcase compartment, said crankcase housing defining a plurality of cylinders, a gas equalizing passage defined by at least one cylinder wall, said gas equalizing passage leading from the interior of said crankcase compartment to at least one suction chamber defined by a cylinder head mounted to said crankcase housing, a valve plate disposed between the crankcase housing and the cylinder head and having a suction port communicating the suction chamber with one of said cylinders, and conduit means connected to said gas equalizing passage to positively direct fluid from said crankcase compartment toward said suction port.

2. A hermetic refrigeration motor compressor unit as claimed in claim 1, wherein said gas equalizing passage is positioned parallel to the axis of each cylinder into which the fluid flow is directed.

3. A hermetic refrigeration motor compressor unit as claimed in claim 1, wherein said fluid passes through said fluid equalizing passage in response to the pressure of fluid in said crankcase compartment and the reciprocation ofa piston movable in said cylinder.

4. A refrigeration motor compressor unit comprising a housing separated by a partition into a crankcase compartment and a motor compartment, said partition also defining an oil return passage connecting said motor compartment with said crankcase compartment, said crankcase compartment defining a plurality of cylinders adapted to receive pistons therein; a valve plate having a plurality of apertures therein mounted to said crankcase compartment, said apertures comprising at least one suction port, a cylinder head mounted to said crankcase compartment and constructed to define at least one suction chamber, a fluid equalizing passage defined by said crankcase compartment housing, conduit means connected to said passage to positively direct fluid flow from said crankcase compartment through said passage toward said suction port.

5. A refrigeration motor compressor unit as claimed in claim 4, wherein one end of said fluid equalizing passage opens into the interior of said crankcase compartment and the other end of said passage opens into a suction chamber in the cylinder head.

6. A refrigeration motor compressor unit as claimed in claim 4, wherein said fluid equalizing passage has one end cooperating with the interior of the crankcase compartment and the other end cooperating with said conduit means.

7. A refrigeration motor compressor unit as claimed in claim 4, wherein said oil return passage has a oneway check valve mounted therein, said one-way check valve allowing fluid flow only from said motor compartment to said crankcase compartment.

8. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means comprises a curved tube. 1 i u 9. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means is equipped with a discharge nozzle, said discharge nozzle being con,- structed to change the velocity of flow of fluid passing through said passage.

10. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means is a plate defining a passage, said plate being adapted to be mounted to said valve plate.

1 l. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means comprises a passage in said valve plate to direct fluid passing through said passage toward such suction port.

12. A hermetic refrigeration motor compressor unit comprising a housing divided by a partition into a crankcase compartment and a motor compartment, said partition defining an oil return passage connecting said motor compartment with said crankcase compartment, said crankcase compartment comprising a housing including a plurality of cylinders adapted to have pistons movably positioned therein, a valve plate mounted to said crankcase housing, said valve plate having a plurality of apertures therein comprising at least one suction port and at least one discharge port, a cylinder head mounted to said crank-case compartment, said cylinder head defining at least one suction chamber, a fluid equalizing passage defined by at least one of said cylinder walls, said fluid equalizing passage having one end opening into said crankcase compartment and the other end opening into at least one of said cylinder head suction chambers, conduit means ,connected to said fluid equalizing passage to direct fluid from said passage towards a suction port of said valve plate in response to the suction stroke of a piston.

13. A hermetic refrigeration motor compressor unit as claimed in claim 12, wherein said fluid equalizing passage is also defined by said valve plate.

14. A hermetic refrigeration motor compressor unit as claimed in claim 12, wherein said conduit means comprises a curved tube member, said tube member being threadably mounted in said fluid equalizing passage to form fluid exit means.

15. A hermetic refrigeration motor compressor unit as claimed in claim 14, wherein said curved tube member is substantially J shaped.

16. A hermetic refrigeration motor compressor unit as claimed in claim 14, wherein said curved tube member is constructed to fit within a cylinder head suction chamber and to direct fluid flowing from said crankcase compartment through said equalizing passage toward a suction port in said valve plate.

17. A hermetically sealed refrigerant motor compressor unit comprising a housing, said housing defining a crankcase compartment including a plurality of cylinders adapted to have pistons mounted for movement therein and a motor compartment, a partition separating said crankcase compartment and said motor compartment with means to allow fluid flow from the motor compartment to the crankcase compartment and prevent fluid flow from the crankcase compartment to the motor compartment, a valve plate mounted adjacent at least one of said cylinders, said valve plate having a plurality of apertures therein, with at least one of said apertures being a suction port, a cylinder head mounted to said valve plate, said cylinder head defining a plurality of chambers, at least one of said chambers being a suction chamber, at least one of said cylinders defining a fluid equalization passage leading from said crankcase compartment interior to a suction chamber in said cylinder head, conduit means interconnected to said fluid equalization passage to direct fluid flowing from said crankcase compartment through said fluid equalization passage toward said at least one valve plate suction port in said cylinder in cooperation with the suction stroke of the piston, said conduit means comprising a curved tube member having one end positioned in a specific direction pointing towards said inlet port.

18. A hermetically sealed refrigerant motor compressor as claimed in claim 17, wherein said conduit means has a discharge nozzle changing the velocity of said fluid stream passing through said passage. 

1. A hermetic refrigeration motor compressor unit of the type having an oil return check valve passage leading from the motor compartment to the compressor crankcase compartment comprising a one-way check valve disposed in said oil return check valve passage to allow oil only to flow from said motor compartment to said compressor crankcase compartment, said crankcase housing defining a plurality of cylinders, a gas equalizing passage defined by at least one cylinder wall, said gas equalizing passage leading from the interior of said crankcase compartment to at least one suction chamber defined by a cylinder head mounted to said crankcase housing, a valve plate disposed between the crankcase housing and the cylinder head and having a suction port communicating the suction chamber with one of said cylinders, and conduit means connected to said gas equalizing passage to positively direct fluid from said crankcase compartment toward said suction port.
 1. A hermetic refrigeration motor compressor unit of the type having an oil return check valve passage leading from the motor compartment to the compressor crankcase compartment comprising a one-way check valve disposed in said oil return check valve passage to allow oil only to flow from said motor compartment to said compressor crankcase compartment, said crankcase housing defining a plurality of cylinders, a gas equalizing passage defined by at least one cylinder wall, said gas equalizing passage leading from the interior of said crankcase compartment to at least one suction chamber defined by a cylinder head mounted to said crankcase housing, a valve plate disposed between the crankcase housing and the cylinder head and having a suction port communicating the suction chamber with one of said cylinders, and conduit means connected to said gas equalizing passage to positively direct fluid from said crankcase compartment toward said suction port.
 2. A hermetic refrigeration motor compressor unit as claimed in claim 1, wherein said gas equalizing passage is positioned parallel to the axis of each cylinder into which the fluid flow is directed.
 3. A hermetic refrigeration motor compressor unit as claimed in claim 1, whereiN said fluid passes through said fluid equalizing passage in response to the pressure of fluid in said crankcase compartment and the reciprocation of a piston movable in said cylinder.
 4. A refrigeration motor compressor unit comprising a housing separated by a partition into a crankcase compartment and a motor compartment, said partition also defining an oil return passage connecting said motor compartment with said crankcase compartment, said crankcase compartment defining a plurality of cylinders adapted to receive pistons therein; a valve plate having a plurality of apertures therein mounted to said crankcase compartment, said apertures comprising at least one suction port, a cylinder head mounted to said crankcase compartment and constructed to define at least one suction chamber, a fluid equalizing passage defined by said crankcase compartment housing, conduit means connected to said passage to positively direct fluid flow from said crankcase compartment through said passage toward said suction port.
 5. A refrigeration motor compressor unit as claimed in claim 4, wherein one end of said fluid equalizing passage opens into the interior of said crankcase compartment and the other end of said passage opens into a suction chamber in the cylinder head.
 6. A refrigeration motor compressor unit as claimed in claim 4, wherein said fluid equalizing passage has one end cooperating with the interior of the crankcase compartment and the other end cooperating with said conduit means.
 7. A refrigeration motor compressor unit as claimed in claim 4, wherein said oil return passage has a one-way check valve mounted therein, said one-way check valve allowing fluid flow only from said motor compartment to said crankcase compartment.
 8. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means comprises a curved tube.
 9. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means is equipped with a discharge nozzle, said discharge nozzle being constructed to change the velocity of flow of fluid passing through said passage.
 10. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means is a plate defining a passage, said plate being adapted to be mounted to said valve plate.
 11. A refrigeration motor compressor unit as claimed in claim 4, wherein said conduit means comprises a passage in said valve plate to direct fluid passing through said passage toward such suction port.
 12. A hermetic refrigeration motor compressor unit comprising a housing divided by a partition into a crankcase compartment and a motor compartment, said partition defining an oil return passage connecting said motor compartment with said crankcase compartment, said crankcase compartment comprising a housing including a plurality of cylinders adapted to have pistons movably positioned therein, a valve plate mounted to said crankcase housing, said valve plate having a plurality of apertures therein comprising at least one suction port and at least one discharge port, a cylinder head mounted to said crank-case compartment, said cylinder head defining at least one suction chamber, a fluid equalizing passage defined by at least one of said cylinder walls, said fluid equalizing passage having one end opening into said crankcase compartment and the other end opening into at least one of said cylinder head suction chambers, conduit means connected to said fluid equalizing passage to direct fluid from said passage towards a suction port of said valve plate in response to the suction stroke of a piston.
 13. A hermetic refrigeration motor compressor unit as claimed in claim 12, wherein said fluid equalizing passage is also defined by said valve plate.
 14. A hermetic refrigeration motor compressor unit as claimed in claim 12, wherein said conduit means comprises a curved tube member, said tube member being threadably mounted in said fluid equalizing passage to form fluid exit means.
 15. A hermetic refrigeratioN motor compressor unit as claimed in claim 14, wherein said curved tube member is substantially ''''J'''' shaped.
 16. A hermetic refrigeration motor compressor unit as claimed in claim 14, wherein said curved tube member is constructed to fit within a cylinder head suction chamber and to direct fluid flowing from said crankcase compartment through said equalizing passage toward a suction port in said valve plate.
 17. A hermetically sealed refrigerant motor compressor unit comprising a housing, said housing defining a crankcase compartment including a plurality of cylinders adapted to have pistons mounted for movement therein and a motor compartment, a partition separating said crankcase compartment and said motor compartment with means to allow fluid flow from the motor compartment to the crankcase compartment and prevent fluid flow from the crankcase compartment to the motor compartment, a valve plate mounted adjacent at least one of said cylinders, said valve plate having a plurality of apertures therein, with at least one of said apertures being a suction port, a cylinder head mounted to said valve plate, said cylinder head defining a plurality of chambers, at least one of said chambers being a suction chamber, at least one of said cylinders defining a fluid equalization passage leading from said crankcase compartment interior to a suction chamber in said cylinder head, conduit means interconnected to said fluid equalization passage to direct fluid flowing from said crankcase compartment through said fluid equalization passage toward said at least one valve plate suction port in said cylinder in cooperation with the suction stroke of the piston, said conduit means comprising a curved tube member having one end positioned in a specific direction pointing towards said inlet port. 